Instruments for removing calculi (e.g., kidney and gallstones) without major surgery are commonly of two general types. One takes the form of an expandable basket as shown and described in patents to Dormia No. 2,943,626, Wallace No. 2,918,919, and Schwartz et al No. 4,046,150. The other form consists of miniaturized grasping forceps having an elongated flexible stem which allow the forceps to be inserted through endoscope passages and through natural or artificially-formed body passages, as disclosed in patents such as Kramer No. 3,334,630, and Chester No. 3,074,408. One problem associated with both types of instruments lies in the possible injury to surrounding tissue as a grasped stone is extracted through the body passage or organ. Such dangers may be reduced by fragmenting the stone in situ with a lithotriptor, but such fragmentation may create additional problems if any of the fragments should remain, provide the nuclei for further stone development, and ultimately occlude the body passages.
Accordingly, it is an object of this invention to provide an instrument that may be used to contain a stone while it remains within the organ or body passage, thereby protecting the surrounding tissues against direct contact with the edges and surfaces of that stone. The instrument may then be used to remove the grasped and contained stone in an unfragmented condition or, alternatively, to fragment the stone in situ with a suitable lithotriptor. If the stone is removed intact, the instrument shields the surrounding tissues against contact that might result in cutting or tearing of such tissues, whereas if the stone is first fragmented, the instrument may be used to contain and extract such fragments.
In brief, one component of the instrument takes the form of an elongated stone-grasping device having a distal working end for grasping calculi. Such a device may be any of a variety of conventional stone baskets or grasping forceps of the types mentioned above. A second component takes the form of a catheter having a lumen which slidably receives the grasping device. The distal end of the catheter terminates in an opening through which the working end of the grasping device may be extended and retracted for the purpose of grasping a stone and drawing it into the end portion of the catheter. The catheter's distal end portion is expandable to receive a stone retained by the working end of the grasping device and contractable to retain the stone or its fragments during an extraction procedure. In the case of fragmentation of the stone prior to extraction, the distal end of the catheter may also serve to protect surrounding tissue from injury that might otherwise be caused by the fragmenting element or the energy release therefrom.
In one embodiment, the distal end portion of the catheter is provided with one or more expandable gussets that permit enlargment of the catheter's distal end as the working end of the grasping device, and the stone grasped thereby, are retracted into the catheter. In another embodiment, the catheter is provided at its distal end with a plurality of circumferentially-spaced flexible struts that, in an untensioned state, spread apart to define an open-ended basket. Adjacent struts of the basket are bridged by a flexible membrane or web. A flexible actuating tube is slidably mounted upon the catheter and engages the struts to close or contract the basket when the tube is shifted distally along the catheter. In a third embodiment, the catheter again has a plurality of flexible struts at its distal end but, unlike the second version, such struts in an untensioned condition have their ends in mutual engagement so that the basket is normally closed. Actuating means in the form of control lines extend longitudinally along the catheter from the struts to the catheter's proximal end so that upon manipulation of such lines the basket may be opened to receive and enclose a stone drawn into the basket by the grasping device. A fourth embodiment is similar to the third, with struts that urge the basket into a normally closed condition, but the actuating means includes an outer actuating tube connected to the struts by the protective membrane that extends over the basket. When the actuating tube is retracted, the membrane is tensioned and the struts are flexed outwardly to open the basket so that the basket may receive and enclose a stone drawn into it by the grasping device.
Other features, objects, and advantages of the invention will become apparent from the drawings and specification.